1. Field of the Invention
The present invention relates to an image processing method, and more particularly to an image processing method in which defects in the color tone of the pupils of a photographed object in a digital image are detected and corrected.
2. Description of the Related Art
Hitherto, there have may many cases in which objects have been photographed such that the color of the photographed object in an image is different from the color of the actual object due to the state of reflection of light during the photographing operation. The foregoing phenomenon, called “red-eye”, looks very unnatural and deteriorates the appearance of the image. Therefore, an image processing is performed to correct the images so that it looks more natural.
If a person is photographed from the front by using an electronic flash, the so-called “red-eye” phenomenon occurs which causes the pupils to be photographed red or gold. The red-eye phenomenon occurs when light of the electronic flash is made incident from the front on the opened eyes of a person in a dark place. In the foregoing state, light is regularly reflected by the eyes. The foregoing state appears in the photographed image. The red-eye phenomenon includes “red-eye” in which the pupils are photographed red and “gold-eye” in which the pupils are photographed gold. (Hereinafter, these two phenomena are collectively called “red-eye”.)
Since red-eye deteriorates the quality of the photograph, a variety of image processing methods for correcting red-eye have been disclosed. For example, a method has been disclosed in Japanese Patent Application Laid-Open (JP-A) No. 7-72537 in which regions including the eyes, which are regions at which red-eye is to be corrected, are designated. Then, threshold value processing of the saturation, luminance and the hue in the designated regions is performed. If pixels are in the regions predetermined threshold values, a determination is made that there is red-eye, and the red-eye is corrected. Another red-eye correction method has been disclosed in Japanese Patent Application Laid-Open (JP-A) No. 9-261580 in which pupil candidate regions are selected in accordance with color information and saturation information about the inside portions of regions surrounded by edges. Then, all of the pupils having defective color tone among the selected pupil candidate regions are corrected so that red-eye is corrected.
The conventional methods disclosed in Japanese Patent Application Laid-Open (JP-A) No. 7-72537 and Japanese Patent Application Laid-Open (JP-A) No. 9-261580 are arranged to perform threshold value processing of the saturation, luminance and the hue so as to determine the red-eye regions which must be corrected. Since the saturation, luminance and the hue of red-eye vary widely, errors in extraction and omissions from extraction cannot be prevented. There is also the concern that a strange image may be formed because flesh color portions may also be blackened in as a result of the process for correcting the red-eye of the pupils.
When extraction of edges of an image is performed as in Japanese Patent Application Laid-Open (JP-A) No. 9-261580, there is the concern that excess divisions or errors in dividing the regions may occur because an image has considerably complicated edges generally.
That is, sectioning into regions is not performed in Japanese Patent Application Laid-Open (JP-A) No. 7-72537 former method. Whether or not red-eye has occurred is determined in accordance with only the threshold values of colors. Therefore, it is easy for a region which does not require correction to be erroneously detected as a region which must be corrected together with a region which must be corrected. Further, Japanese Patent Application Laid-Open (JP-A) No. 9-261580 cannot accurately section the regions. Therefore, there arises the problem that it is difficult to correct only the pupil region which is the area which is the object of correction.
Hitherto, printing onto a photosensitive material of an image photographed on a photographic film (hereinafter called a “film”), such as a negative film or a reversal film, has been performed by direct exposure in which images on the film are projected to planarly expose of the surface of the photosensitive material. On the other hand, a digital photographic system has been put into practical use in which image information photographed on, for example, a film is photoelectrically read are converted into digital data which is then subjected to a variety of image processings. Thereafter, the photosensitive material is exposed in a digital manner.
The foregoing digital photographic system basically includes an image reading section, such as a scanner, for reading an image recorded on an original, such as a translucent original or a reflected original, to produce corresponding image data; an image processing section for subjecting image data inputted thereto to a variety of image processings and an image recording section having a printer for digitally exposing the photosensitive material in accordance with the to processed image data and a processor for developing the exposed photosensitive material and the like.
In the digital photographic system, the image of an original is read by the scanner. The read image is converted into digital image data. In the image processing section, image processing conditions (exposing conditions) are determined in accordance with the image data, and then a variety of image processings are performed. In the printer, the photosensitive material is scanned and exposed in accordance with processed image data so that a latent image is recorded. Then, a development process suitable for the photosensitive material is performed by the processor. As a result, a finished print is produced in which the image photographed on the film is reproduced.
The digital photographic system is able to shorten the time required to complete the exposure, that is, can quickly complete the exposure. Moreover, image information of the finished print can be stored on a recording medium, such as a magneto-optical disk. Therefore, re-reading of the film is not required and the operation for printing extra copies can quickly and easily be performed. Moreover, image processings such as editing operations (e.g., image synthesis and image division) and color/density adjustment can arbitrarily be performed. Therefore, an advantage can be realized in that a finished print which has been freely subjected to editing and image processings as needed can be output.
One of the important factors influencing the quality of the image of a portrait photograph is the reproducibility of the eyes of a human being. In particular, the red-eye phenomenon in which the eyes are photographed red due to the effects of the electronic flash or the like is a serious problem. Even in a case of a photograph of a satisfactory quality and free from the red-eye phenomenon, light must be reflected and shone in each eye. That is, if the catch light in the eye is expressed in the photograph too weakly, there arises a problem in that a portrait photograph having a satisfactory image quality cannot be obtained.
To solve the above-mentioned problems, the applicant of the present application proposed an image processing method and apparatus in Japanese Patent Application Laid-Open (JP-A) No. 10-75374. That is, the eye region is extracted from a region designated by an operator and including the eyes, and then determination of red-eye of the eye region is performed. If it is determined that there is red-eye, a red-eye eliminating process is performed. A catch light determination is performed after the eye region has been extracted. If a determination is made that the catch light is too weak, a process for enhancing the catch light is performed.
The above-described image processing method and apparatus disclosed in Japanese Patent Application Laid-Open (JP-A) No. 10-75374 enable correction of dark eyes to be performed by lowering the saturation of the eye region to make the color close to an achromatic color in a case of dark eyes. However, in a case of blue eyes, for example, the desired hue of blue is instructed in advance and stored, and conversion of the hue is carried out so as to perform correction for blue eyes. However, there arises a problem in that the difference in the hue from that of the eye of the photographed person can be recognized in the case of a close-up photograph of the eyes. In this case, an unsettling image is formed.